mail.itcex.se has no CNAME records.
Question and response
Question
dig mail.itcex.se. NS
Answer
The response has no answer records.
Authority
itcex.se. 637 SOA dns3.itconnection.se. registry.itconnection.se. 1564670231 3600 1200 1209600 7200
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0